The Surveillance, Epidemiology, and End Results (SEER) Program was established by the National Cancer Institute (NCI) to collect and report periodically on population-based cancer incidence and survival data. It is a core component of the NCI's surveillance activities which provide information used for planning cancer control and research programs, and for evaluating the impact of such programs on cancer rates. The SEER Program was initiated in 1972 in response to requirements of the National Cancer Program for assessing the magnitude of the cancer burden in the United States, and for identifying factors related to cancer risk and/or patient survival. Objectives of the SEER Program include: 1. Assemble and report, on a periodic basis, estimates of cancer incidence. 2. Monitor annual cancer incidence trends to identify unusual changes in specific forms of cancer occurring in population subgroups defined by geographic, demographic, and social characteristics. 3. Provide continuing information on changes over time in extent of disease at diagnosis, trends in therapy, and changes in cancer patient survival. 4. Identify the occurrence of possible iatrogenic cancers, i.e., cancers that are caused by cancer therapy. 5. Serve as a research resource to the National Cancer Institute, and conduct studies dealing with current cancer control issues as well as issues related to the operation of the SEER Program which may lead to improved and/or more cost-effective operating procedures.